Improved process for asymmetric hydrogenation

摘要

The present invention is a process for the preparation of a compound of the formula:where R3, R4 and n are defined in the specification which comprises hydrogenating a compound of the formula:the E-geometrical isomer thereof or a mixture of the Z- and E-isomers in the presence of catalyst containing Rh, a chiral ligand with at least one phosphorous atom where the hydrogenation is conducted in the presence of a base.